[SemanticDB] Support TypeApply Synthetic

[tanishiking]

#13135

This PR adds support Inferred Type Application to Synthetic. See https://scalameta.org/docs/semanticdb/specification.html#synthetic-1

val lst = List(1)
lst.map(_ + 2)

// synthetic
val lst = List.apply[Int](1)
lst.map[Int](_ + 2)

Synthetic(
  <List>,
  TypeApplyTree(
    SelectTree(
      OriginalTree(<List>),
      IdTree(<apply>)
    ),
    List(TypeRef(None, <Int>, List()))
  )
)
Synthetic(
  <lst.map>,
  TypeApplyTree(
    OriginalTree(<lst.map>),
    List(TypeRef(None, <Int>, List()))
  ))

[tanishiking]

Unlike scala2, we don't have [4:6..4:19): (left, right) => *.apply[Int, Int] because actually we don't have it.

-Xprint:typer shows:

before

  val (left, right) = (1, 2)

after

    private[this] val $1$: (Int, Int) = Tuple2.apply[Int, Int](1, 2)
    val left: Int = this.$1$._1
    val right: Int = this.$1$._2

[tanishiking]

I didn't add synthesized Tuple2.apply[Int, Int](*) to Synthetic section, because Scala2 doesn't include it (even though there is synthesized Tuple2.apply )

[bishabosha]

maybe something can be done here with tree attachments, this case only occurs when a pattern is exactly identifiers in a tuple:

https://github.com/dotty-staging/dotty/blob/82677dab26eb2c9bd6c978f6bbf4d5318d797cc6/compiler/src/dotty/tools/dotc/ast/Desugar.scala#L1126-L1128

[bishabosha]

or at least the code linked above deals with all desugaring of patterns in val definitions so the door is open for other patterns than tuples

[bishabosha]

this needs a rebase

[smarter]

What's the status of this PR? It needs a rebase but otherwise can it be merged @bishabosha ?

[bishabosha]

I think it was just about improving support for Tuple patterns in a val definition, but that could be done in a later PR

[tanishiking]

sorry i'd been busy and couldn't update it, I'll rebase onto master later.

[bishabosha]

I rebased and re-ran from sbt scala3-compiler/Test/runMain dotty.tools.dotc.semanticdb.updateExpect

[tanishiking]

Ah, sorry for the late response, and thank you for rebasing (and of course reviewing)!